https://bmcanesthesiol.biomedcentral.com/articles/10.1186/1471-2253-10-9
https://bmcanesthesiol.biomedcentral.com/articles/10.1186/1471-2253-10-8
https://bmcanesthesiol.biomedcentral.com/articles/10.1186/1471-2253-10-10
https://bmcanesthesiol.biomedcentral.com/articles/10.1186/1471-2253-10-11